1. Global climate change and Oregon’s water resources Philip Mote Climate Impacts Group University of Washington Alan Hamlet (UW), Iris Stewart (UCSD) With thanks to Dave Hart, Jon Lea, Greg Johnson, Randy Julander, Scott Pattee ftp://ftp.atmos.washington.edu/philip/SNOWPAPER/

2. The Climate Impacts Group Goal: help the region become more resilient to climate variations and climate change Supported by NOAA Office of Global Programs http://cses.washington.edu/

3. Main points Human influence on climate has already emerged Hydrologic changes in Oregon have been profound and will continue

4. Earth’s radiation budget From Kiehl and Trenberth, 1996

5. Science of climate change Thousands of peer-reviewed scientific papers Intergovernmental Panel on Climate Change (IPCC) Major reports in 1990, 1996, 2001, 2007 Conclusions: – “An increasing body of observations gives a collective picture of a warming world and other changes in the climate system.” –“There is new and stronger evidence that most of the warming observed over the last 50 years is attributable to human activities.”

6. Carbon dioxide: up 32%

7. HALOE H 2 O Convection Frequency(0.5, 1, 5, 10%) Tropopause Global Surface Temperature Variations Randel et al 2001, fig 6

8. Larsen B Ice shelf Antarctica January 31, 2002 MODIS data Courtesy NSIDC

9. February 17

10. February 23

11. March 5

12. 1928 2000 The South Cascade glacier retreated dramatically in the 20th century Courtesy of the USGS glacier group

13. At almost every USHCN station, winters warmed + signs: warming but not statistically significant

14. Natural Climate InfluenceHuman Climate Influence All Climate Influences

15. Main points Human influence on climate has already emerged Hydrologic changes in Oregon have been profound and will continue

17. Snake River at Ice Harbor

18. As the West warms, winter flows rise and summer flows drop Figure by Iris Stewart, Scripps Inst. of Oceanog. (UC San Diego)

19. March June Relative Trend (% per year) Trends in fraction of annual runoff for cells with more than 50 mm of SWE on April 1

20. Stewart et al., 2004; Stewart et al., in press, J. Clim. Spring-pulse dates Centers of Mass By several measures, Western snowfed streamflow has been arriving earlier in the year in recent decades Spring pulse Center time

21. Relative trends 1950-1997 in April 1 SWE

22. Trends in Simulated Average APR 1 SWE for the Cascades in WA and OR (1950-1995) Effects of TMP and PCP -54% Effects of TMP -26%Effects of PCP -28% SWE (mm)

23. Trends in timing of peak snowpack Change in Date Figure by Alan Hamlet, UW

24. Natural Climate InfluenceHuman Climate Influence All Climate Influences

25. 21 st century temperature change IPCC (www.ipcc.ch)

26. Planning for climate change: water resources in the Columbia basin Water policy workshops have highlighted the need to inject climate change information into existing river basin planning activities and to provide free access to streamflow scenarios. www.ce.washington.edu/~hamleaf/climate_change_streamflows/CR_cc.htm Partners: Northwest Power Planning Council Idaho Dept of Water Resources

27. Simulated Natural Flow in the Willamette River at the Confluence with the Columbia

28. Simulated Natural Flow at Pelton Dam on the Deschutes River

29. Main points Human influence on climate has already emerged Hydrologic changes in Oregon have been profound and will continue Planning is essential

30. Examples of climate-change planning Portland, Seattle * NWPCC * IDWR CRITFC * CalFed * CEC * ACoE * Quantitative study